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Exploring the origins of the universe from the bottom of the world: Stanford's 31st Bunyan Lecture

Astrophysicist John Carlstrom will talk about his research at the South Pole, where he peers back into time to study "fossil light" from the beginnings of the universe.

By Bjorn Carey

In order to study what happened in the seconds immediately following the Big Bang, John Carlstrom went to Antarctica. It just so happens that one of the most inhospitable places on Earth provides some of the best conditions for pointing a telescope to the stars and glimpsing the remnants of "fossil light" emitted when the universe was born almost 14 billion years ago.

Carlstrom, a professor with the Kavli Institute for Cosmological Physics at the University of Chicago, will provide further insight into these experiments during Stanford's 31st annual Bunyan Lecture, hosted by the Astronomy Program, to be held Tuesday, Feb. 25.

In his lecture, titled Exploring the Origins of the Universe from the Bottom of the World, Carlstrom will detail some of the dramatic and surprising astronomical discoveries from the past few decades that have revealed an astonishing amount of insight into the origin, evolution and make-up of the universe. He will also explore some of the mysterious cosmological elements that scientists predict must exist, but know very little about, such as dark matter and dark energy.

The Bunyan Lecture is named for James T. Bunyan, a member of the Hoover Institution whose will specified that his estate endow lectures that "inquire into man's changing vision of the cosmos and of human destiny as revealed in the latest discoveries in the fields of astronomy and space exploration."

"We try to make Bunyan's wishes come true by inviting exceptional astronomers to enlighten the Stanford community, and John Carlstrom is certainly one of the two or three leaders in the field of cosmic microwave background fluctuation and polarization, if not the leader," said Vahe Petrosian, a professor of physics and of applied physics and chairman of the Astronomy Program. "He elucidates the initial conditions of what the universe comes from, and everything else we do follows what he studies."

Antarctica is cold enough to freeze any water moisture out of the air that would otherwise distort light, and the telescope is actually two miles above sea level, meaning there's less atmosphere to interfere with incoming light. These qualities make the icy continent the best place on Earth to study the cosmic microwave background (CMB), defined generally as the radiation coming to us from the Big Bang.

Using the 10-meter South Pole Telescope, Carlstrom's team has produced the highest resolution images of the CMB. In addition to providing baseline information that can be used to test various theories about the origin and makeup of the universe, objects in front of the CMB cast a "shadow," which scientists use to measure the evolution of the universe.

"It's very exciting," he said, "to look at this data and see how the universe evolved from its infancy to present day."

Going forward, by measuring the polarization of light from the CMB, Carlstrom hopes to infer the first instants of the universe, dialing the clock back to a tiny fraction of a second after the Big Bang.

"This research has been great fun. When you look at the light from the early universe, you're measuring ripples across the sky that actually trace sound waves in the young universe," Carlstrom said. "One of the first things we showed is that it has a beautiful spectrum, like the universe was ringing like a bell."

John Carlstrom will speak at 7:30 p.m. Feb. 25 in Braun Auditorium in the Mudd Chemistry Building, 333 Campus Drive.